Re: [PATCH v4 1/5] ACPI / processor_idle: introduce ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE

[Sudeep Holla]

On 20/04/16 10:56, Vikas Sajjan wrote:
> Hi Sudeep,
>
> On Tue, Apr 19, 2016 at 6:00 PM, Sudeep Holla <sudeep.holla@xxxxxxx> wrote:
> > ACPI 6.0 adds a new method to specify the CPU idle states(C-states)
> > called Low Power Idle(LPI) states. Since new architectures like ARM64
> > use only LPIs, introduce ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE to
> > encapsulate all the code supporting the old style C-states(_CST)
> >
> > This patch will help to extend the processor_idle module to support
> > LPI.

[...]

> > @@ -1018,29 +1062,11 @@ int acpi_processor_power_init(struct acpi_processor *pr)
> >          acpi_status status;
> >          int retval;
> >          struct cpuidle_device *dev;
> > -       static int first_run;
> >
> >          if (disabled_by_idle_boot_param())
> >                  return 0;
> >
> > -       if (!first_run) {
> > -               dmi_check_system(processor_power_dmi_table);
> > -               max_cstate = acpi_processor_cstate_check(max_cstate);
> > -               if (max_cstate < ACPI_C_STATES_MAX)
> > -                       printk(KERN_NOTICE
> > -                              "ACPI: processor limited to max C-state %d\n",
> > -                              max_cstate);
> > -               first_run++;
> > -       }
> > -
> > -       if (acpi_gbl_FADT.cst_control && !nocst) {
> > -               status =
> > -                   acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
> > -               if (ACPI_FAILURE(status)) {
> > -                       ACPI_EXCEPTION((AE_INFO, status,
> > -                                       "Notifying BIOS of _CST ability failed"));
> > -               }
> > -       }
> > +       acpi_processor_cstate_first_run_checks();
> >
> >          acpi_processor_get_power_info(pr);
> >          pr->flags.power_setup_done = 1;
>
> Not related to your change,
> The acpi_processor_get_power_info() function can return failure, so i
> thought it makes sense to check for the return value
> and then set the  flag pr->flags.power_setup_done appropriately.

Makes sense, will do that.

--
Regards,
Sudeep